CP BIOLOGY
ECOLOGY AND ENERGY FLOW NOTES
ECOLOGY
 scientific study of interactions among organisms and between organisms and
their environment

Biosphere
o contains all living organisms
o includes, land, water, and air
o dynamic, ever-changing
o organisms interdependent with each other and environments

Levels of Organization
o species  populations  communities  ecosystem  biome 
biosphere
o species: group of organisms that can breed with each other and
produce fertile offspring
o populations: groups of individuals of same species in same area
o communities: the various populations living in same area
o ecosystem: all organisms living in area and includes nonliving
environment
o biome: group of ecosystems with same climate and similar
communities
ENERGY FLOW
 flow of energy through ecosystem one of most important factors
determining a system’s capacity to sustain life

Producers
o sunlight = main energy source for life on Earth
o < 1% of sun’s energy used by living things
o some organisms – energy stored in chemical compounds (don’t get their
energy from sun)
o autotrophs = organisms that capture energy from sun to make own
food, also called producers
CP BIOLOGY, ECOLOGY AND ENERGY FLOW NOTES, page 2

Producers, cont’d
o most producers make food through photosynthesis (CO2 + H2O  O2 +
sugars)
o land = plants, water = algae, bacteria
o in places with no sunlight, producers make food through
chemosynthesis
 bacteria
 volcanic vents, hot springs, tidal marshes

Consumers
o organisms that cannot use sunlight directly
o rely on other organisms for energy and food = heterotrophs
(consumers)
o many types:
 herbivores: eat plants, ex. cow, deer
 carnivores: eat animals, ex. snakes, owls
 omnivores: eat plants and animals, ex. humans, bears
 detritivores: eat dead matter (plant and animal), ex.
earthworms, snails
o important group of heterotrophs = decomposers
 break down organic matter
 bacteria and fungi

Feeding Relationships
o energy flows through ecosystem in one direction: sun  autotrophs 
heterotrophs
o food chains = series of steps in which organisms transfer energy by
eating and being eaten
o examples:
 grass  antelope  coyote (2 steps)
 algae  zooplankton  herring  squid  shark (4 steps)
o food webs = network of food chains in an ecosystem, involve complex
interactions
o trophic level = each step in food chain/web
 producers – 1st
 consumers – 2nd, 3rd, or higher (each level depends on one below)
CP BIOLOGY, ECOLOGY AND ENERGY NOTES, page 3

Ecological Pyramids
o diagram showing relative amounts of energy or matter contained
within each trophic level in food chain/web
o three types:
 Energy Pyramid
 at each level only some of energy passed to next because
some of energy used (respiration, movement,
reproduction)
 only about 10% of energy in a level transferred to next
level
 more levels between producer and top level consumer –
less energy remains from original amount
 Biomass Pyramid
 biomass = total amount of living tissue in a trophic level
(grams/ unit area)
 represents amount of potential food available for each
trophic level in an ecosystem
 Pyramid of Numbers
 shows numbers of individual organisms in each trophic
level
 some ecosystems have pyramid of numbers with same
shape as their energy and biomass pyramids
 other ecosystems – pyramid of numbers may not look like
a pyramid (ex. forests)